Further Studies on the Roles of Sodium and Potassium in the Generation of the Electro-Olfactogram

Abstract

A B S T R A C TIn the negative EOG-generating process a cation which can substitute for Na + was sought among the monovalent ions, Li +, Rb +, Cs +, NH4 +, and TEA +, the divalent ions, Mg ++, Ca ++, Sr ++, Ba ++, Zn++, Cd++, Mn ++, Co ++, and Ni ++, and the trivalent ions, A1 +++ and Fe II z. In Ringer solutions in which Na + was replaced by one of these cations the negative EOG's decreased in amplitude and could not maintain the original amplitudes. In K+-Ringer solution in which Na + was replaced by K +, the negative EOG's reversed their polarity. Recovery of these reversed potentials was examined in modified Ringer solutions in which Na + was replaced by one of the above cations. Complete recovery was found only in the normal Ringer solution. Thus, it was clarified that Na + plays an irreplaceable role in the generation of the negative EOG's. The sieve hypothesis which was valid for the positive EOG-generating membrane or IPSP was not found applicable in any form to the negative EOGgenerating membrane. The reversal of the negative EOG's found in K +-, Rb +-, and Ba++-Ringer solutions was attributed to the exit of the internal K +. It is, however, not known whether or not C1-permeability increases in these Na+-free solutions and contributes to the generation of the reversed EOG's.The ionic mechanisms underlying the generation of the electro-negative and positive "electro-olfactograms" (EOG's) have been studied in previous papers (Takagi and Wyse, 1965;Takagi, Wyse, and Yajima, 1966;Takagi, 1968; Takagi, Wyse, Kitamura, and Ito, 1968). Briefly, the results showed that the negative EOG's primarily depend upon the entry of Na+ and the simultaneous exit of K +, and that neither Li +, tetraethyl a m m o n i u m (TEA+), choline +, hydrazine, nor sucrose can substitute for Na+; the positive EOG's primarily depend upon the entry of CI-and the simultaneous exit of K +, and three anions, Br-, F-, and H C O~ can substitute for C1-.

Current recording from sensory cilia of olfactory receptor cells in situ. II. Role of mucosal Na+, K+, and Ca2+ ions.

“…Our finding is in agreement with the report of Takagi et al (1969), that for the generation of the normal, negative EOG, mucosal and serosal Na ÷ ions were necessary and could not be substituted by any of the mono-, di-, or trivalent cations that they used. Of course, the odorant-induced compound EOG, based on receptor currents of many ORCs (Ottoson, 1956(Ottoson, , 1971, may contain non-Na + components in addition.…”

“…EOGs represent compound signals from in situ receptor cells and from glia-like sustentacular cells of the olfactory mucosa. The EOG response to mucosal cation substitution suggested that the charge carriers of odor-induced currents are either Na + (Takagi et al, 1969) or Ca 2+ (Suzuki, 1978;Winegar et al, 1988). Alternatively, based on EOGs it was claimed that cations do not give rise to receptor currents (Yoshii and Kurihara, 1983).…”

Effect of Deepwater Horizon Crude Oil Water Accommodated Fraction on Olfactory Function in the Atlantic Stingray, Hypanus sabinus

“…Cysteine was the only amino acid that generated a positive EOG response in oil exposed stingrays and a normal negative EOG response in stingrays that were exposed to untreated seawater conditions. This phenomenon has not been documented previously in either teleosts or elasmobranchs but it has been documented in frogs 50 , newts 51 , and tortoises 52 . One example that has caused a positive EOG is when barium ions and a degenerated epithelium caused the blocking of chloride ions from entering the cell but not potassium ions from exiting the cell 50 , 52 .…”

Odorant response of isolated olfactory receptor cells is blocked by amiloride

“…The nasal mucosa responds to odorants with an inwardly directed short-circuit current which depends on the presence of Na ions in the mucosal solution [65]. Recently it was shown that part of the "chemosensory" inward current is blocked by amiloride, an inhibitor of several Na-transport systems.…”